If you had protected intercourse last month and during the flu , then it is unlikely that you would be pregnant even you have missed your periods by 5 days now. however it is better that you get a urine pregnancy test done to rule out pregnancy to allay your anxiety.
Th delay can be due to stress induced by illness during the month which can cause hormonal imbalances and a possible delay in menses. I hope i have answered your query in detail,
wishing you good health,
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.